Fish-oil supplements may do more harm than good, UBC researcher finds

Research from the University of British Columbia’s Okanagan campus is calling into question the value of fish-oil based supplements as a way to combat cardiac and inflammatory disease.

Photograph by: File photo
, Postmedia News

Groundbreaking research at the University of British Columbia’s Okanagan campus is calling into question the value of fish-oil based supplements as a way to combat cardiac and inflammatory disease.

Fish oil supplements fed to mice already on a diet rich in vegetable oil interfered with the ability of cells in the gastrointestinal system to repair themselves, according to recent research by Sanjoy Ghosh, an assistant professor of biology, published in the British Journal of Nutrition.

Additional unpublished results point to a similar effect on cardiac tissues.

Damaging oxidative stress appears to be caused by the combination of omega-6 fatty acids in vegetable-based oils and the omega-3 fatty acids in fish oil, according to Ghosh.

In the past 50 years, North Americans have replaced much of the saturated fat in their diet with unsaturated fats, dramatically increasing their consumption of omega-6 polyunsaturated fatty acids and altering the balance of omega-3 and omega-6 fatty acids.

Previous studies of human populations that consume large amounts of omega-3 fatty acids as part of their normal diet suggest a protective effect against cardiac and inflammatory disease.

But when researchers added the omega-3 rich fish oil to the diet of mice to see if it would reduce the inflammation caused by omega-6 rich vegetable oils, they were stunned when it made matters worse.

“Our hypothesis is that levels of omega 6 are so high in our bodies that any more unsaturated fatty acid — even omega 3, despite its health benefits — will actually contribute to the negative effects omega 6 PUFA have on the heart and gut,” said Ghosh. “When there is too much [polyunsaturated fatty acid], the body doesn’t know what to do with it.”

This is not the first time that Ghosh has produced findings that turned popular notions about nutrition and health on their head.

As a graduate student Ghosh discovered by accident that so-called “heart healthy” oils rich in Omega-6 polyunsaturated fatty acids inflicted damage to the hearts of rats and neo-natal pigs.

The result was so shocking that Ghosh was turned down for publication by all the major scientific journals. The results of the rat-based study were eventually published by the journal Nutrition in 2004.

Subsequent research vindicated Ghosh and opened up a new line of scientific inquiry questioning popularly held notions about the health benefits of vegetable based oils.

“Vegetable based oils like corn and canola were promoted to the public as a healthier alternative to animal-based fats, but there was never any research that said they are any healthier,” said Ghosh.

In fact, recent research has linked excessive levels of omega-6 to colitis, insulin resistance, diabetes and obesity, he said. And people’s attempts to “balance” omega-6 levels with omega-3 supplements may be damaging their health.

“There is no magic pill that fixes a bad diet,” he said.

“The vast majority of studies that show omega 3 oils are beneficial are based on eating fish, not pills,” he said. “When you eat a lot of fish you automatically eat less of other oils and it’s a healthier balance.”

The polyunsaturated fats in vegetable oils have only been added to the human diet very recently, roughly coinciding with a steady rise in diet-related illness, he said.

A diet that includes foods rich in saturated fats, such as cheese and butter, and healthy unsaturated fats, such as those in olive oil and nuts will promote a more natural balance of fats, not unlike the Mediterranean diet, he said.

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